HIV Flashcards
what does HIV target in general
immune cells
what are the two tyoes of HIV
HIV 1 - more commonly associated with AIDS
HIV 2 - rarer and restricted to Africa and asia
specifically, what does HIV 1 target
CD4+ cells such as macrophages, T helper cells and dendritic cells
what is the function of cd4
helps immune cells communicate with each other when fighting foreign pathogens
how can people be naturally immune to HIV
hiv needs not only to bind to cd4 but also a coreceptor before it can invade a cell. if someone has a mutation which alters the shape of their co receptor then HIV cannot invade
describe HIV as a pathogen
single stranded RNA retrovirus (uses reverse transcriptase to copy itself)
how does HIV replicate itself
invades immune cell then copies its RNA via reverse transcriptase. This proviral DNA then integrates into the immune cells (host) DNA ready to be replicated. every time the host is exposed to infection, as the t cell replicates, so does the HIV
how does HIV typically spread from person to person
sexual
parenteral (needlestick)
vertical (mother to child)
what happens as soon as a person is infected with HIV
dendritic cells eat infection from mucosa and take it to nearest lymph node, the infection then takes over all the immune cells in the lymph node leading to a very high viral load in acute infection
what are the symptoms of acute infection of HIV
flu like symptoms similar to glandular fever
how long is the acute phase
12 weeks
what happens to the viral load from acute and chronic phases
decreases as the hosts immune system attempts to control replication and counterattack
how long can the chronic phase last for
2-10 years
what happens to t cells in the chronic phase
as the virus increases the t cells decrease killing roughly 2 billion cells per day
you end up with around 500 T cells which is just enough to fight infections even though they may be more sever
what happens if t cells drop to roughly 200-500 cells
lymphadenopathy
hairy leukoplakia (white patches on tongue caused by EBV)
oral candida
what happens if the t cells drop below 200
immune system severely compromised leading to AIDS
persistent fever fatigue weight loss and diarrhoea with HIV count rising
what are the AIDS defining conditions
recurrent bacterial pneumonia
pneumocystis pneumonia
fungal infections (candida of the oesophagus)
tumours (kaposis sarcoma, primary lymphoma of the brain)
what is the most common mode of transmission
male to male in developed countries
male to female in developing countries
IVDU
how can you diagnose HIV
antibody testing (elisa or rapid tests)
antibody (antiHIV) antigen (p24) testing
RNA/ DNA test
treatment
antiretroviral therapy (triple therapy)
transmission is unlikely if
viral load is less than 400 copies /ml
what are the main confirmatory tests done for hiv
HIV antibody differentiation immunoassay
western blot
what do you monitor after treatment initiation
cd4 count viral rna load
cd4/cd8 ratio
what are the main types of anti retroviral drugs
NRTI NNRTI nucleotide analogues protease inhibitors integrase inhibitors fusion inhibitor ccr5 antagonist
most NRTIs end in
ine
most proteasi inhibitors end in
avir
most integrase inhibitors end in
gravir
what defines AIDS
cd4<200
aids defining conditions
what are the aids defining conditions
primary lymphoma of the brain
pneumocystis pneumonia
cerebral toxoplasmosis
what virus causes kaposis sarcoma
hhv8
